[Ebola fever: an emerging disease]

One of the most fatal diseases encountered by mankind so far is Ebola fever. Ebola fever is caused by a highly pathogenic virus from the Filoviridae family which is found in nature in four different sub-types which differ among others also by their pathogenicity for man. The hitherto detected EBO sub-types are stable do not change in the course of an epidemic nor in the course of the patient's illness, nor during passage of the virus from one subject to another. The author presents a historical review of epidemics, nosocomial and laboratory infections, spread and epizoonosis caused by the Ebola virus. The author presents a detailed clinical picture describing the frequency and evolution of different clinical symptoms and signs based on the observation of 103 patients infected with the Ebola virus in Kikwit, Zaire (nowadays Democratic Republic of Congo) in 1995. In the laboratory diagnosis individual tests are mentioned assessing the presence of the virus, viral antigens and antibodies, incl. the most recent immunohistochemical test. The author mentions the problem of patient care and his therapy, incl. available antiviral drugs and passive immunotherapy. He also discusses the possibility and probability of spread of the Ebola virus into our environment. He mentions principles for transport of subjects with suspected disease, demands for their strict isolation and maximum protection of the attending staff incl. barrier nursing technique. The author discusses also principles of epidemiological work, detection and isolation of sources, identification and follow up of contacts and epidemiological supervision of affected areas. Past epidemics made it possible to assemble many scientific findings and practical experience. These make it possible to cope nowadays with any attack of the Ebola virus not only in areas of its epizootic occurrence.

[Bioterrorism--a public and health threat]

In recent years the fear of bioterrorism, of secret modernization and dissemination of biological weapons is increasing. Facts detected recently in Iran, Japan and the former Soviet Union provide evidence that there are countries and dissident groups which have access to modern technology of cultivation of dangerous pathogens as well as motivation for their use in acts of terrorism or war. The menace of biological terrorism is nowadays, as compared with the past, much greater. The most feared candidates as regards production of biological weapons are the pathogens of smallpox, anthrax and plague. The author discusses the serious character of possible events associated with terrorist dissemination of these pathogens. It is much esier to produce and use biological weapons than to create effective systems of defence against them. The menace of bioterrorism and bioweapons must not be exaggerated nor underestimated. The possible terrorist use of bioweapons is real. At present even the most advanced industrial countries cannot quarantee effective protection of their populations. Fortunately they are however aware of their present vulnerability. Our society is not equipped to cope with bioterrorism. Preparation and reinforcement of the health services, in particular of sections specialized in the control of infectious diseases is an effective step to divert the sequelae and suffering associated with terrorist use of biological agents. It is essential to be prepared. This calls for time and funds which unfortunately are not plentiful.

[20 years without smallpox]

It is 20 years since the 33rd World Health Assembly (WHA) declared that "worldwide eradication of smallpox" was achieved. This was the outcome of many years intensive work of the World Health Organization (WHO) and its member countries. In 1958 the WHA adopted the recommendation that WHO should initiate the eradication of smallpox on a worldwide scale. In 1967 the eradication activities in hitherto endemic countries became more intense. Smallpox affected 31 countries and 15 countries recorded from occasional cases. Every year more than 10 million people contracted the disease and two million of them died. A ten-year limit for the eradication was set. Gradually smallpox were eradicated in South America, then in Asia and last in Africa where the last case of endemic smallpox was recorded in 1977 in Somalia. WHO ensured international collaboration, close coordination of activities and mobilization of financial, personal and material resources. It ensured also that tested methods were fully applied in the affected countries regardless of their political, religious and cultural differences. In the eradication activities participated hundreds of thousands of local and 700 health professionals from abroad, incl. 20 Czechoslovak epidemiologists. The worldwide costs of eradication amounted to some 300 million dollars, i.e. some 23 million per year. The most important contribution of the eradication of smallpox was in addition to the termination of human suffering, worldwide financial savings estimated to 1-2 billion US dollars per year. These saved personal and financial resources could be used for other important health projects. The eradication of variola was defined as eradication of clinical forms of smallpox not as the final eradication of the variola virus. The importance of laboratories keeping the variola virus increased steeply at the time when clinical cases of smallpox were eradicated. From the beginning of the eighties WHO made an effort to reduce their number to a minimum. Since 1984 strains of variola are officially kept only in two centres collaborating with WHO. The Organization suggested destruction of the kept viruses in 1987, i.e. ten years after the eradication of smallpox. Unfortunately some political and scientific circles did not agree with this intention. Even recommendations to destroy the virus in 1993 and again in 1999 were not accepted. In the nineties fear of bio-terrorism and secret modernization of biological weapons influenced some member countries to change their opinion on the intended destruction of the virus. Despite this in May 1999 the WHA adopted a resolution that the final destruction of all variola strains is the objective of all member countries of WHO and recommended to postpone the destruction of the virus to the year 2002. The reason for postponement is current research of new antiviral preparations and better vaccines. There is again hope that all that will be left of the variola virus will be magnetic signals on computer diskettes.

Ebola between outbreaks: intensified Ebola hemorrhagic fever surveillance in the Democratic Republic of the Congo, 1981-1985

Surveillance for Ebola hemorrhagic fever was conducted in the Democratic Republic of the Congo from 1981 to 1985 to estimate the incidence of human infection. Persons who met the criteria of one of three different case definitions were clinically evaluated, and blood was obtained for antibody confirmation by IFA. Contacts of each case and 4 age- and sex-matched controls were also clinically examined and tested for immunofluorescent antibody. Twenty-one cases of Ebola infection (persons with an antibody titer of > or = 1:64, or lower if they fit the clinical case definition) were identified, with a maximum 1-year incidence of 9 and a case fatality rate of 43%. Cases occurred throughout the year, but most (48%) occurred early in the rainy season. Fifteen percent of contacts had antibody titers > or =1:64 to Ebola virus, compared with 1% of controls (P < .0001). Results suggest that Ebola virus periodically emerges from nature to infect humans, that person-to-person transmission is relatively limited, and that amplification to large epidemics is unusual.

Risk factors for HIV infection among abandoned Romanian children

OBJECTIVE

To determine risk factors for HIV infection among abandoned Romanian infants and children living in a public institution.

METHODS

A cross-sectional study was conducted in June 1990 among 101 children between 0 and 4 years of age living in an orphanage. Orphanage and hospital records were reviewed and a blood specimen for hepatitis B and HIV serologic testing obtained from each child. A case-control study was conducted using data from the cross-sectional study. Cases were HIV-positive children; one HIV-negative control, matched by age, was selected for each case.

RESULTS

Overall, 20 (20%) children were HIV-positive, 88 (87%) tested positive for antibody to hepatitis B core antigen, and 32 (32%) were hepatitis B surface antigen-positive. In the case-control study, HIV-positive children had received more therapeutic injections [mean, 280; median, 231] than age-matched HIV-negative children [mean; 142, median, 155; P = 0.02]. Cases were more likely than controls to have received over 200 lifetime injections (odds ratio, 5.7; 95% confidence interval, 1.2-32.7). Blood transfusions and mother-to-child transmission were excluded as routes of HIV transmission. By reviewing sterilization records and interviewing local health-care workers, we determined that needles and syringes were often re-used without proper disinfection in the orphanage.

CONCLUSIONS

These data provide strong epidemiologic evidence that indiscriminate injections with contaminated needles and syringes were responsible for HIV transmission in this population.

Acquired immunodeficiency syndrome in Romania

After the initial description of acquired immunodeficiency syndrome (AIDS) in Romania in late 1989, national AIDS case surveillance was established with a modified version of the World Health Organisation (WHO) clinical case definition. This modified case definition requires that AIDS cases have both clinical and serological evidence of human immunodeficiency virus (HIV) infection. Before December, 1989, Romania had reported 13 AIDS cases to WHO. By Dec 31, 1990, 1168 AIDS cases were reported to Romania's Ministry of Health, of which 1094 (93.7%) occurred in children less than 13 years of age at diagnosis. Of these, 1086 (99.3%) were in infants and children less than 4 years of age, and 683 (62.4%) in abandoned children living in public institutions at the time of diagnosis. By Dec 31, 1990, 493 (45.1%) mothers of children with AIDS had been located and tested, and 37 (7.5%) were positive for HIV; 423 (38.7%) cases were in children who had received transfusions of unscreened blood, and 6 (0.5%) were in children with clotting disorders. HIV transmission through the improper use of needles and syringes is strongly suspected in most of the remaining 628 (57.4%) children with AIDS, most of whom had received multiple therapeutic injections. This outbreak demonstrates the serious potential for HIV transmission in medical facilities that intensively and improperly use parenteral therapy and have poor sterilisation technique.

Human monkeypox: confusion with chickenpox

Human monkeypox is a zoonosis occurring sporadically in the tropical rain forest of western and central Africa. The exact incidence and geographical distribution are unknown, since many cases are not recognized. Special surveillance was established in three regions in Zaire in 1981 that led to a substantial increase in reported cases. The question arose as to the possibility that clinical diagnostic errors cause some cases of monkeypox to be misdiagnosed as other eruptive diseases. This paper presents the results of a study assessing the extent of and reasons for these clinical diagnostic errors in areas where health staff as well as the general public are aware of human monkeypox. In Zaire in the period 1981-1986, 977 persons with skin eruption not clinically diagnosed as human monkeypox were laboratory tested. 3.3% of human monkeypox cases were found among 730 patients diagnosed as cases of chickenpox, 7.3% among cases diagnosed as "atypical chickenpox" and 6.1% among cases with skin rash for which clinical diagnosis could not be established. The diagnostic difficulties were mainly based on clinical features characteristic of chickenpox: regional pleomorphism (in 46% of misdiagnosed cases), indefinite body-distribution of skin eruptions (49%), and centripetal distribution of skin lesions (17%). Lymph-node enlargement was observed in 76% of misdiagnosed patients. In the absence of smallpox, the main clinical diagnostic problem is the differentiation of human monkeypox from chickenpox. The presence of lymphadenopathy, pre-eruptive fever and slower maturation of skin lesions are the most important clinical signs supporting correct diagnosis of monkeypox.

The transmission potential of monkeypox virus in human populations

Data on monkeypox in Zaire over the five years 1980-1984 are analysed to assess the protection imparted by past smallpox vaccination and the transmission potential of the virus in unvaccinated communities. Attack rates in individuals with and without vaccination scars indicated that smallpox vaccination (discontinued in 1980) imparted approximately 85% protection against monkeypox. It is predicted that monkeypox virus will continue to be introduced into human communities from animal sources, and that the average magnitude and duration of monkeypox epidemics will increase as vaccine-derived protection declines in the population. On the other hand, current evidence indicates that the virus is appreciably less transmissible than was smallpox, and that it will not persist in human communities, even in the total absence of vaccination. The findings thus support the recommendation of the Global Commission for the Certification of Smallpox Eradication to cease routine smallpox vaccination in monkeypox endemic areas, but to encourage continued epidemiological surveillance.

[Human monkey pox: its clinico-epidemiological characteristics]

During the course of the smallpox eradication programme, a new eruptive disease clinically resembling smallpox was discovered in Zaire. The disease, which was named monkeypox after the virus, is a zoonosis occurring sporadically in countries of western and central Africa with tropical rain forest. The studies carried out in Zaire from 1980 through 1985 showed that monkeypox affects mainly children in relatively small remote villages whose population has traditionally frequent contacts with wild animals. Apart from the wildlife, the virus can be transmitted from man to man, but among other sources of infection sick persons did not exceed 20%. Presumed human transmission has occurred in 38 out of 61 outbreaks of human monkeypox and only once reached the third and once the fourth generation; the transmission in all affected villages under observation has extinguished itself. Considering the sporadic and relatively rare occurrence of the disease and expected complications following the immunization with vaccinia which protects from monkeypox, introduction of mass vaccination in the areas at risk is hardly justified at present.

Human monkeypox: disease pattern, incidence and attack rates in a rural area of northern Zaire

Human monkeypox is a zoonosis that occurs sporadically in the tropical rainforest of western and central Africa. This article presents the results of epidemiological features of 91 monkeypox patients reported in Bumba zone in northern Zaire during the period 1981 to 1985. Their age ranged from 7 months to 29 years (93% below 15 years of age). 11% of patients had visible smallpox vaccination scars. Deaths occurred sporadically; the overall case-fatality rate was 9%. 91 patients arose in 61 separate outbreaks; 42 of them consisted of only a single case. The source of infection was suspected to be animal for 70 cases, and human for the remaining 21 cases. The illness occurred in all months of the year. There was a considerable clustering of cases in the northern part of the zone. The average annual incidence rate in the observed zone was 0.63 cases per 10,000 population with marked differences in age, time and place. The average annual primary attack rate among unvaccinated individuals (1.7/10,000) sharply contrasted with those vaccinated (0.04/10,000). The secondary attack rate for contacts without vaccination scar (4.3%) differed significantly from those who had been vaccinated in past (0.7%). Many unvaccinated contacts living under conditions of maximal exposure to index cases escaped not only the disease but also infection. The low incidence rate of human monkeypox indicates its limited public health importance even in a well-known enzootic area.

Human monkeypox: secondary attack rates

Data on human monkeypox collected in Zaire during the six years 1981-86 were analysed to assess the extent of interhuman transmission of monkeypox virus. Among the 2278 persons who had close contact with 245 monkeypox patients infected from an animal source, 93 fell ill and were presumed to have been infected from the known human source: 69 of these were spread in the first generation, 19 in the second generation, and the remaining five cases in the third and fourth generation.The secondary attack rates were correlated with the age, sex, place of residence, and vaccination status of the contacts. There was an overall 3% probability of becoming ill following infection from a known human source. The affected household was the main focal point for interhuman transmission of monkeypox virus. The highest attack rate (11.7%) occurred among unvaccinated household contacts in the age group 0-4 years. However, the majority of susceptible persons who had been close to patients in the confined space of poorly ventilated huts failed to develop illness. There was no evidence of an increase in the secondary attack rate between 1970-80 and 1981-86.The inefficient spread from person to person, even in conditions of maximum exposure, supports the concept that monkeypox virus is poorly adapted for sustained transmission between humans and that such transmission does not pose a significant health problem.

Monkeypox virus: ecology and public health significance

Recent investigations have revealed that monkeypox virus infections occur with a high prevalence in several species of squirrels belonging to the genus Funisciurus, less frequently in squirrels of the genus Heliosciurus, and rarely in forest-dwelling primates. These squirrels commonly inhabit the secondary forests around human settlements in the rural areas of Zaire, especially where oil palms are grown, and are rare in the primary rain forest.Human infection with monkeypox virus occurs most frequently in the 5-9-year-old age group, particularly in small villages where the children hunt and eat squirrels and other small mammals. As the populations are now increasing in number and can no longer feed on wild life alone for their animal protein requirements, the development of animal husbandry as a source of meat will certainly decrease the risk and the incidence of human monkeypox, even in areas where monkeypox virus is present in the local population of squirrels.Although population growth and economic development in western and central Africa will probably reduce the risk of human infection with monkeypox virus, visitors to these areas who are likely to come into contact with wild animals should be offered smallpox vaccination as a protection.

Clinico-epidemiological features of monkeypox patients with an animal or human source of infection

Clinical and laboratory examinations were carried out on a total of 338 monkeypox patients in Zaire from 1981 to 1986. An animal source of infection was suspected in 245 (72%) and interhuman transmission for the remaining 93 patients. Among those whose infection was presumably acquired from an animal source, the most affected groups were children aged 3-4 years (27%) and 5-6 years (20%), while only 4% of cases were over 15 years old; there was a considerable preponderance of males (58%) over females (42%), especially in the age group 5-14 years. Among those presumably infected by person-to-person transmission, the age distribution was more uniform, adult patients tending to be relatively more common, and there were more females (57%) than males (43%).Based on comparisons of the frequency and intensity of clinical signs and symptoms among patients infected from an animal source and those who were infected by another patient, there was no evidence that the disease becomes more severe and the transmitted virus more virulent or more easily transmissible from person to person after one or more passages through human hosts.

Stochastic model for interhuman spread of monkeypox

With the eradication of smallpox, systematic routine vaccination with vaccinia has ceased and an increasing proportion of the human population in tropical rain forest areas of central and western Africa lacks vaccinia-derived immunity to monkeypox virus. This raises the question of the ability of monkeypox virus to establish and maintain itself in an unvaccinated population through continuous man-to-man transmission. A computerized stochastic model of Monte Carlo type was constructed to assess this potential risk. Simulated series were repeated 100 times to obtain distributions of predicted outcomes for decreasing levels of vaccination coverage (70 per cent, 50 per cent, and 0 per cent). The results revealed a substantial increase in new secondary cases in the total absence of vaccinia-induced immunity. Nevertheless, none of the simulated series did lead to an "explosive" epidemic. The model clearly indicated diminishing numbers of cases in successive generations and eventual cessation of transmission. Therefore, it appears highly improbable that the virus could maintain itself permanently in communities by interhuman transmission. After the eradication of smallpox, human monkeypox constitutes the most important orthopoxvirus infection in man, but analysis of information collected up to this time suggests that it does not represent currently a serious public health problem or a challenge to the achieved eradication of smallpox.

Human monkeypox: clinical features of 282 patients

We present the clinical features and course of 282 patients with human monkeypox in Zaire during 1980-1985. The ages of the patients ranged from one month to 69 years; 90% were less than 15 years of age. The clinical picture was similar to that of the ordinary and modified forms of smallpox. Lymphadenopathy, occurring in the early stage of the illness, was the most important sign differentiating human monkeypox from smallpox and chickenpox. The symptoms, signs, and the course of the disease in patients who had been vaccinated against smallpox differed significantly from those in unvaccinated subjects. Pleomorphism and "cropping" similar to that in chickenpox occurred in 31% of vaccinated and 18% of unvaccinated patients. The prognosis depended largely on the presence of severe complications. No deaths occurred among vaccinated patients. In unvaccinated patients the crude case-fatality rate was 11% but was higher among the youngest children (15%).

The role of squirrels in sustaining monkeypox virus transmission

When the research on the ecology of monkeypox virus entered the latest stage in 1984, three groups of animals were considered priority candidates for maintenance of virus circulations in nature because of their relatively higher population density: terrestrial rodents, squirrels, and gregarious bats. Following the isolation of the virus from a wild squirrel in 1985 another survey was carried out in Bumba zone of Zaïre in January-February 1986, which included collection of animal samples, later on tested by WHO collaborating laboratories. No antibodies were found in 233 rodents tested. A high prevalence of monkeypox-specific antibodies (24.7%) found in 320 squirrels of Funisciurus anerythrus species suggested that these animals sustain virus transmission in the areas surrounding human settlements. A consistently high level of antibody prevalence found among squirrels Heliosciurus rufobrachium suggested that this species is also steadily involved in the transmission. The squirrels, the only mammals frequently infected by monkeypox in the areas of human activities, which are frequently trapped by the population, are obviously a major source of infection for human beings. Out of 39 primates collected during the survey from the primary forest, three were found seropositive for monkeypox. At the moment, however, it is difficult to say whether the primates play an important role in sustaining virus transmission in nature, or (like human beings) that they are an occasional host of the virus. Possibilities are discussed of monkeypox virus transmission being sustained by squirrels outside the areas of major human activities.

Serological survey for human monkeypox infections in a selected population in Zaire

About 3460 persons living in Kole zone of East Kasai, in Zaire, were examined and their sera screened initially by a haemagglutination-inhibition test. Of these, 667 (19%) were positive. Radioimmunoassay adsorption tests for the presence of monkeypox- or vaccinia-specific antibodies gave unequivocal results in 300 of these sera; the remaining 47 were nonspecific. Monkeypox-specific antibodies were found in sera of 27 individuals, of all ages and both sexes, giving an overall prevalence rate of monkeypox virus-specific antibodies of 0.8%. The prevalence rate was four times higher in the 5 to 9 year age group (1.3%) than in children aged 0 to 4 years (0.3%), and was highest (2.4%) in the 15 to 19 year age group. There was no significant difference in the prevalence rates between the sexes. As might be expected, there are substantially higher prevalence rates in persons living in forest galleries than in those in savannah, and among those living in areas where human monkeypox cases had occurred in the past compared with those living in other localities. Nineteen children whose sera showed specific monkeypox antibodies were re-examined. Twelve showed facial and body skin changes suggesting the presence of vesiculo-pustular disease in the past; four of these had been known registered monkeypox cases. Seven children had neither signs nor history of past vesiculo-pustular disease, suggesting that they had suffered from subclinical infection with monkeypox virus.

Human monkeypox: a study of 2,510 contacts of 214 patients

A study of 2,510 contacts of 214 patients with human monkeypox was conducted in Zaire from 1980 to 1984. Among the contacts of 130 primary cases of human monkeypox, a further 22 co-primary and 62 secondary cases were detected, and an additional fourteen people who had no evidence of clinical disease had positive serological results. A majority of the clinical and subclinical cases of monkeypox occurred in children less than 10 years of age. Immunity in vaccinated persons now appears to be waning because 16 overt cases occurred in contacts who had been vaccinated. The overall attack rate for contacts without a vaccination scar (7.2%) differed significantly from the attack rate for those who had been vaccinated in the past (0.9%). The attack rate for household contacts was significantly higher than that for other contacts, among both unvaccinated (four times higher) and vaccinated (seven times higher) household contacts. Many unvaccinated contacts living in the same household as the index case under conditions of maximum exposure, however, escaped not only the disease but also infection.

Four generations of probable person-to-person transmission of human monkeypox

This paper examines an outbreak of five cases of human monkeypox which occurred in children belonging to two families living in the West Kasai region of Zaire during May-July 1983. Epidemiologic investigations suggest that the first case was infected from an animal source, possibly a monkey, and that each of the other four cases was infected from a previous human case. Three of these cases of presumed person-to-person transmission occurred in close household contacts. The other case infection occurred either by casual contact within the hospital compound, or possibly because of infection due to use of the same syringe for injections. Human monkeypox is the most important orthopoxvirus infection in the post-smallpox eradication period. The disease is a zoonosis and person-to-person transmission is rather difficult. Thus, this episode is a rare event and special analysis of the circumstances is discussed. However, it supports the necessity to carry out surveillance and research on this disease as recently reported by Arita et al.

[Contagiousness of monkey pox for humans: results of an investigation of 2 outbreaks of the infection in Zaire]

The results of the investigation of two outbreaks of group monkeypox infection among humans (altogether 8 cases) in the zone of Bumba, Equatorial Province, Zaire, are presented. The primary source of infection in both outbreaks was not established, the outbreaks were supposedly caused by sick wild animals. Almost all persons affected by this infection were children aged 7 months to 7 years, never vaccinated against smallpox; the only exception was a 29-year old female patient, formerly vaccinated and revaccinated against smallpox. During one of the outbreaks the laboratory-confirmed transmission of infection from man to man was established in two generations. During the other outbreak there were grounds to suspect the transmission of infection in three generations, though the possibility of contacting infection from animals could not be completely ruled out. The existence of the inapparent form of monkeypox in humans was revealed.

Human monkeypox: a newly emerged orthopoxvirus zoonosis in the tropical rain forests of Africa

During the course of the recently concluded smallpox eradication program, a new human orthopoxvirus infection was discovered which is caused by monkeypox virus. The disease occurs sporadically in remote villages within tropical rain forests of West and Central Africa. The disease is rare; only 155 cases having been reported from 1970 to 1983. The symptoms and signs of human monkeypox resemble those of smallpox, differing significantly only in the occurrence of lymphadenopathy with human monkeypox disease. Of 155 cases, some 80% are believed to have resulted from infection from an as yet unknown animal reservoir; the rest occurred among unvaccinated close contacts among whom a secondary attack rate of 15% was observed. Although person-to-person spread appears to have occurred in some instances, few cases were observed in the third or fourth generation of transmission and none thereafter. Since 1982, the incidence of human monkeypox infections in Zaire has increased concomitant with an intensified surveillance program. Additional reasons which might explain the increased incidence are discussed. Further surveillance and research of this primarily zoonotic infection are warranted and are in progress.

Human tanapox in Zaire: clinical and epidemiological observations on cases confirmed by laboratory studies

Human tanapox, a mild disease characterized by a short febrile illness associated with one or more skin lesions, is important because of its possible confusion with smallpox. The article describes clinical and epidemiological features of 264 laboratory-confirmed tanapox cases observed in a geographically limited area in northern Zaire over the period 1979-83.

Human monkeypox transmitted by a chimpanzee in a tropical rain-forest area of Zaire

A case of monkeypox infection in a six-month-old baby girl who had been bitten by a wild chimpanzee in Kivu, Zaire, was investigated. The child had not been exposed to any monkeypox-like disease and no cases of such disease had occurred in the surrounding area during previous months. The time of onset of rash was consistent with the virus having been transmitted from the chimpanzee. However, it is still not known whether chimpanzees and other primates or lower mammals are the primary reservoir of monkeypox infection.

Facial scarring after varicella. A comparison with variola major and variola minor

To assess the prevalence of persistent facial scars after recovery from chickenpox (varicella), 250 subjects in Somalia in whom the diagnosis had been confirmed by electron microscopic identification of varicella virus were examined in 1979, a year after their illness; 2.4% had five or more facial scars indistinguishable from those seen among smallpox (variola major or variola minor) victims, with a higher percentage among males (2.7%) than females (1.9%). The highest proportion of those with five or more residual facial scars (8.3%) was found among young adults 20-29-years-old. The low proportion of varicella cases who had five or more facial scars contrasts with the 6.8% of cases of variola minor who were similarly scarred one year later (Somalia, 1978), and to an even greater degree with the situation after variola major, where the proportion varied from 65% for vaccinated subjects to 85% among unvaccinated persons (India, 1976). Pockmark surveys are a valid method for determining the past occurrence of variola major but cannot be relied on in areas were variola minor has occurred. However, varicella must be considered when making such a retrospective diagnosis.

Residual skin changes in patients who have recovered from variola minor

In order to assess the frequency of occurrence of facial pockmarks after recovery from variola minor, 175 subjects from 5 localities in Somalia were carefully examined a year after recovery from variola minor infections. Only 7% had facial pockmarks (the usual criteria for "positive" classification in facial pockmark surveys). Thus, pockmark surveys cannot be considered useful for evaluating the past smallpox situation in areas where variola minor has been prevalent. A number of other subjects had discolorations of the skin on their faces or bodies, but these are of dubious value for survey purposes.

The world's last endemic case of smallpox: surveillance and containment measures

On 31 October 1977, the world's last known case of endemic smallpox was discovered in Merca, Somalia. The source of infection was quickly identified; 19 days previously, the male patient had been in contact with two other cases for not more than 15 minutes, but the surveillance activities surrounding these cases did not identify him as a contact. The patient was isolated and containment and surveillance activities and a vaccination campaign were rapidly instituted; 161 contacts were identified, 41 of whom had not been vaccinated within the last three years. The patient recovered and fortunately no other cases occurred.

Common-source epidemic of hepatitis due to glazed and iced pastries

Sixty-one clinical cases of hepatitis occurred in Ogemaw County, Michigan, in late April and May 1968. The clustering of cases in time and the high attack rate for persons 10-19 years of age suggested a common source of exposure. Investigation implicated a local bakery, where one of the employees directly involved in the baking had had an icteric illness one month before the outbreak. Comparison of exposure histories of patients versus healthy family members established pastries covered with glaze or icing as the vehicle of infection. The glaze and icing were applied to the pastries after all baking had been completed. During the epidemic, immune serum globulin was given on a community-wide basis. No secondary cases of hepatitis were identified.

Epidemiological and clinical study of tuberculosis in the district of Kolin, Czechoslovakia. Report for the first 4 years of the study (1961-64)

Many developed countries are faced with the problem of reorganizing their tuberculosis-control programme to bring it into line with modern conditions. The study reported was undertaken to provide guidelines for this reorganization. It was begun in the district of Kolín, Czechoslovakia, with a population of some 100 000, in 1961 and is still in progress. The paper covers the first 4 years of the study.In 1961 a thorough check-up was made on all persons registered as having active or inactive tuberculosis, or fibrotic lung lesions. In 1961 and 1963 a mass X-ray and tuberculin-testing campaign, with 95% coverage, was carried out for all persons over 14 years of age. All persons with active tuberculosis received adequate treatment. Persons registered as having tuberculosis or suspected tuberculosis were subjected to regular photofluorographic and bacteriological investigations. Newborn infants were given BCG vaccination, and persons aged 14 years and 19 years with negative tuberculin reactions were vaccinated.The prevalence of bacillary tuberculosis fell from 150 cases in 1960 to 91 in 1964, mainly owing to a decrease in the number of chronic cases. The incidence of bacillary tuberculosis detectable by direct smear microscopy, however, remained at about 25 cases throughout the period 1961-64. The risk of developing tuberculosis was found to be highest in persons with fibrotic lung lesions or inactive tuberculosis, and in men above 45 years of age and women above 65 with previously normal photofluorograms.It is concluded from the study that in developed countries priority should be given to adequate treatment of all persons with active tuberculosis, and to early diagnosis in persons consulting physicians and in the high-risk population groups.